* [PATCH v4 1/2] nvme-multipath: expose path_state via sysfs
2026-07-24 9:00 [PATCH v4 0/2] nvme-multipath: expose path_state via sysfs Guixin Liu
@ 2026-07-24 9:00 ` Guixin Liu
2026-07-24 9:00 ` [PATCH v4 2/2] nvme-multipath: document path_state sysfs attribute Guixin Liu
1 sibling, 0 replies; 3+ messages in thread
From: Guixin Liu @ 2026-07-24 9:00 UTC (permalink / raw)
To: Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg,
Nilay Shroff, Daniel Wagner, John Garry
Cc: linux-nvme
Add a read-only "path_state" sysfs attribute to each NVMe path namespace
device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
current path state, including whether the path is enabled or disabled
with a specific reason.
Factor the path disable checks from nvme_path_is_disabled() into a new
nvme_path_get_state() helper that returns an enum nvme_path_state. This
keeps the path selection logic and sysfs reporting in sync, so any future
updates to the path disable criteria are automatically reflected in the
sysfs output.
Possible values:
- "enabled" : path is usable for I/O
- "ctrl-down" : controller is not live
- "ana-pending" : ANA state change pending
- "ns-not-ready" : namespace is not ready
This gives userspace visibility into the multipath path selection state
without requiring users to piece together controller state and namespace
flags manually.
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
---
drivers/nvme/host/multipath.c | 47 ++++++++++++++++++++++++++++++-----
drivers/nvme/host/nvme.h | 1 +
drivers/nvme/host/sysfs.c | 4 ++-
3 files changed, 45 insertions(+), 7 deletions(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 9b9a657fa330..84230ac02a48 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -288,7 +288,14 @@ void nvme_mpath_revalidate_paths(struct nvme_ns_head *head)
kblockd_schedule_work(&head->requeue_work);
}
-static bool nvme_path_is_disabled(struct nvme_ns *ns)
+enum nvme_path_state {
+ NVME_PATH_ENABLED,
+ NVME_PATH_DISABLED_CTRL_DOWN,
+ NVME_PATH_DISABLED_ANA_PENDING,
+ NVME_PATH_DISABLED_NS_NOT_READY,
+};
+
+static enum nvme_path_state nvme_path_get_state(struct nvme_ns *ns)
{
enum nvme_ctrl_state state = nvme_ctrl_state(ns->ctrl);
@@ -298,11 +305,17 @@ static bool nvme_path_is_disabled(struct nvme_ns *ns)
* Otherwise it will fail immediately and return to the requeue list.
*/
if (state != NVME_CTRL_LIVE && state != NVME_CTRL_DELETING)
- return true;
- if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
- !test_bit(NVME_NS_READY, &ns->flags))
- return true;
- return false;
+ return NVME_PATH_DISABLED_CTRL_DOWN;
+ if (test_bit(NVME_NS_ANA_PENDING, &ns->flags))
+ return NVME_PATH_DISABLED_ANA_PENDING;
+ if (!test_bit(NVME_NS_READY, &ns->flags))
+ return NVME_PATH_DISABLED_NS_NOT_READY;
+ return NVME_PATH_ENABLED;
+}
+
+static bool nvme_path_is_disabled(struct nvme_ns *ns)
+{
+ return nvme_path_get_state(ns) != NVME_PATH_ENABLED;
}
static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
@@ -1105,6 +1118,28 @@ static ssize_t queue_depth_show(struct device *dev,
}
DEVICE_ATTR_RO(queue_depth);
+static const char * const nvme_path_state_names[] = {
+ [NVME_PATH_ENABLED] = "enabled",
+ [NVME_PATH_DISABLED_CTRL_DOWN] = "ctrl-down",
+ [NVME_PATH_DISABLED_ANA_PENDING] = "ana-pending",
+ [NVME_PATH_DISABLED_NS_NOT_READY] = "ns-not-ready",
+};
+
+static ssize_t path_state_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
+ enum nvme_path_state state = nvme_path_get_state(ns);
+ const char *name = "unknown";
+
+ if (state < ARRAY_SIZE(nvme_path_state_names) &&
+ nvme_path_state_names[state])
+ name = nvme_path_state_names[state];
+
+ return sysfs_emit(buf, "%s\n", name);
+}
+DEVICE_ATTR_RO(path_state);
+
static ssize_t numa_nodes_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 824651cc898d..9a9af2a24136 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -1075,6 +1075,7 @@ extern struct device_attribute dev_attr_ana_grpid;
extern struct device_attribute dev_attr_ana_state;
extern struct device_attribute dev_attr_queue_depth;
extern struct device_attribute dev_attr_numa_nodes;
+extern struct device_attribute dev_attr_path_state;
extern struct device_attribute dev_attr_delayed_removal_secs;
extern struct device_attribute dev_attr_multipath_failover_count;
extern struct device_attribute dev_attr_io_requeue_no_usable_path_count;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 75b2d69b5957..c457a2c67c0b 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -261,6 +261,7 @@ static struct attribute *nvme_ns_attrs[] = {
&dev_attr_ana_state.attr,
&dev_attr_queue_depth.attr,
&dev_attr_numa_nodes.attr,
+ &dev_attr_path_state.attr,
&dev_attr_delayed_removal_secs.attr,
#endif
&dev_attr_io_passthru_err_log_enabled.attr,
@@ -294,7 +295,8 @@ static umode_t nvme_ns_attrs_are_visible(struct kobject *kobj,
if (!nvme_ctrl_use_ana(nvme_get_ns_from_dev(dev)->ctrl))
return 0;
}
- if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr) {
+ if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr ||
+ a == &dev_attr_path_state.attr) {
if (nvme_disk_is_ns_head(dev_to_disk(dev)))
return 0;
}
--
2.43.7
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v4 2/2] nvme-multipath: document path_state sysfs attribute
2026-07-24 9:00 [PATCH v4 0/2] nvme-multipath: expose path_state via sysfs Guixin Liu
2026-07-24 9:00 ` [PATCH v4 1/2] " Guixin Liu
@ 2026-07-24 9:00 ` Guixin Liu
1 sibling, 0 replies; 3+ messages in thread
From: Guixin Liu @ 2026-07-24 9:00 UTC (permalink / raw)
To: Keith Busch, Jens Axboe, Christoph Hellwig, Sagi Grimberg,
Nilay Shroff, Daniel Wagner, John Garry
Cc: linux-nvme
Document the newly added /sys/block/nvmeXcYnZ/path_state attribute in
the stable NVMe sysfs ABI file, describing the possible path states and
their meaning.
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
---
Documentation/ABI/stable/sysfs-nvme | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/Documentation/ABI/stable/sysfs-nvme b/Documentation/ABI/stable/sysfs-nvme
index a2f5d0710db4..04bcea5bae45 100644
--- a/Documentation/ABI/stable/sysfs-nvme
+++ b/Documentation/ABI/stable/sysfs-nvme
@@ -326,6 +326,27 @@ Description:
currently selected path. Returns empty if iopolicy is not
"numa". Requires CONFIG_NVME_MULTIPATH.
+What: /sys/block/nvmeXcYnZ/path_state
+Date: July 2026
+KernelVersion: 7.2
+Contact: Guixin Liu <kanie@linux.alibaba.com>
+Description:
+ Shows the current multipath path state for this namespace
+ path device. Possible values:
+
+ "enabled": the path is usable for I/O.
+
+ "ctrl-down": the path is disabled because the controller
+ is not live.
+
+ "ana-pending": the path is disabled because an ANA state
+ change is pending.
+
+ "ns-not-ready": the path is disabled because the namespace
+ is not ready.
+
+ Requires CONFIG_NVME_MULTIPATH.
+
What: /sys/block/nvmeXnY/delayed_removal_secs
Date: May 2025
KernelVersion: 6.16
--
2.43.7
^ permalink raw reply related [flat|nested] 3+ messages in thread